Azure Functions: how to set CORS via automation?

Question

I have an azure function app that I would like to set up in repeatable (automated) manner so that I can duplicate it in different environments/resource groups. I'm able to create the function app via the azure cli, but I also need to configure the CORS options such that I can call it from a browser.

I've found where to do that in the azure portal web ui, in the 'Platform Features' tab(https://docs.microsoft.com/en-us/azure/azure-functions/functions-how-to-use-azure-function-app-settings#cors), but I can't find anything about modifying that setting via azure cli, or by the VSTS deployment task that I've set up to do releases when I change the functions in the app.

It seems you can even specify the CORS setting for local development via the local.settisg.json, but that only applies locally (https://docs.microsoft.com/en-us/azure/azure-functions/functions-run-local#local-settings). Were I deploying the app via the azure function tools cli I could supposedly specify the --publish-local-settings flag when I deploy, but I'm not deploying that way.

It seems like there must be a way to modify the CORS configuration without using the web UI, am I just not finding it?

Answer 1

Fabio's answer is correct, Azure Resource Manager templates work for this. Since the example he linked to was about logic apps and not azure functions, the getting the template right required a few changes and I wanted to add some detail that may help others get there faster.

To craft the template I ended up downloading the automation template from the function app that I created manually, and then deleting stuff until I got to what I think is the minimum. Here's what I'm using:

{
  "$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "function_app_name": {
      "defaultValue": "my-function-app",
      "type": "string"
    }
  },
  "variables": {},
  "resources": [
    {
      "comments": "CORS allow origins *.",
      "type": "Microsoft.Web/sites/config",
      "name": "[concat(parameters('function_app_name'), '/web')]",
      "apiVersion": "2016-08-01",
      "properties": {
        "cors": {
          "allowedOrigins": [
            "*"
          ]
        }
      },
      "dependsOn": []
    }
  ]
}

I also have a parameters file that goes with this that looks like this:

{
    "$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentParameters.json#",
    "contentVersion": "1.0.0.0",
    "parameters": {
        "function_app_name": {
            "value": null
        }
    }
}

and then I have an Azure Resource Group Deployment step in my release definition that deploys this and substitutes the desired function app name depending on the environment I'm deploying to.

Answer 2

To set CORS settings programatically, you want to use ARM.

Here's an example you can follow: https://msftplayground.com/2016/08/setting-api-definition-url-cors-value-arm/